Prior to the advent of high quality computer-generated page images, page images such as those found in newspapers, newsletters, magazines and the like were formed by graphic artists composing the page images by hand. During the process of combining each different element on a page image, including text, photographs, constant color areas or graphs such as pie charts, and sampled or continuously changing images such as sweeps, the graphic artist could consult with the creators of each of the elements to determine what features of each element were most important to preserve (e.g., “sharp edges”, “depth of tone”, and so on). Thus the operator was able to optimally form each element on the page, independent of the other elements, by processing each according to the creator's selected features during the combining process.
Because these page images, including one or more of these elements, were composed by hand, each element was inherently treated independently of the others according to the desired features for that element. Thus, the optimal halftone screen design for a particular photograph with a large sky area, which may differ from the optimal halftone screen design for a different photograph with skin tones, could be optimally selected and arranged to an optimal angle according to the imaging processes expressed and carried along with the particular photograph with the large sky area.
With the advent of digital color workstations, copiers and printers, creators of page images who would previously have had to rely on graphic artists to compose and print their page images could instead create, compose, and print them on their own using a computer connected to the digital color copier/printer. However, most digital systems for creating a page image, decomposing the page image into print engine instructions, and controlling the print engine to print the page treated a page image as a single, unitary image. Creators of pages using such digital systems were unable to specify specific processes for rendering the individual page elements. Thus, elements which might have benefited from the use of a halftone screen that emphasized sharp edges, such as a photograph containing many fine lines, were nevertheless treated the same as elements that might have needed to suppress engine noise, such as a large headline color text area where mottle and streaking would be visible within the large letters.
U.S. Pat. No. 5,704,021 to Smith et al., Adaptive Color Rendering By an Inkjet Printer Based on Object Type, describes a method of using a printer system for identifying one or more different types of color objects in a document, selecting a preferred rendering option such as halftoning and/or color matching for each one of such different color object types, respectively, and then printing the document in accordance with the rendering options selected for each of such different color object types. U.S. Pat. No. 5,579,446 to Naik et al., Manual/Automatic User Option for Color Printing of Different Types of Objects, describes an interactive user interface which allows a choice between one “button” automatic control of color output or multi-button control of color output, with both automatic and manual options providing independent control for color halftoning and for color correction based on the types of objects to be printed.
While the foregoing system is an improvement over the single, unitary page system, there are several problems with this user interface. First, this user interface system provides only for selections based on object types, such as “photo”, “text”, and “other graphics”. Using an object's type to decide on image processing actions, in some cases, is simply only a rough approximation. For example, large text may not benefit from the same halftone as small text, because a smooth interior color may be more important for large text than the extremely sharp edges which are crucial to small text. Text above a certain size will have a very visible interior, and may exhibit noticeable quality defects if a compact, edge-sharpening halftone is chosen instead of a coarser halftone that provides robust color transfer and therefore reduces the tiny color deletions known as mottle in the interior. Both cases are text, but two different halftone choices may be called for. As a second example, one scanned photo image may contain fine lines with important edge information while a different scanned image may need large tone depth and smooth color transitions for realistic color. Both are photos, but two different halftones and color maps are needed for optimal printing. It would be desirable to have a system by which rendering can be selected based on more information than simply an object's type.
Second, since this user interface maps object types to printer dependent processes, it requires expert knowledge by the user of the printing response for every printer used and every media desired to be used. Most users are not familiar with the response of each printer to printer-dependent imaging action combinations to effectively improve quality. Deciding the low-level color processing combinations to use to get the best results for each object type demands that users have intimate, expert knowledge of a particular printing system and its responses to all combinations of the low-level color processing choices presented. Even if the user is experienced, the problem is compounded in a networked printer environment, where a file could be sent to any of a number of different color printers. To get optimal quality from all the printers no matter which one is used, a user must now have intimate knowledge of the effect of image processing action combinations on each of the printers on the network.
Third, the user interface system does not take into account the media being used as part of the data deciding what printer imaging actions to take. In addition to being familiar with a printer's image processing actions, an experienced user must also be familiar with how different media are printed on the same printer. The response of any given printer, for example, to both halftone and color map tables varies considerably depending on the media being printed on. For example, the halftone used on smooth, synthetic paper would be optimally different from that used to create the same effect on textured papers or heavy papers. Each media responds differently to the deposition of ink or toner and therefore needs different image processing for optimal results. It would be desirable to have a method which will account both the printer and the media being used as factors in determining printer-dependent imaging actions to take.